It began with a message from a source known only as John Doe: my life is in danger. Attached were 2.6 terabytes of data, 11.5 million documents from the Panamanian law firm Mossack Fonseca, some dating back to the 1970s. This episode follows how Bastian Obermayer of the Süddeutsche Zeitung brought in the International Consortium of Investigative Journalists, and how 107 media organizations in 80 countries worked in secret for more than a year, using character recognition software and a graph database to connect people to more than 214,000 offshore entities.

A shell company is not a crime in itself. Stanley Kubrick’s estate used offshore holding companies to shield his English manor from double taxation. But a system built to ask no questions also served drug cartels, sanctions evaders, and politicians, and its hidden money flowed into property in London and Vancouver, pricing out ordinary buyers. The leak named 12 current or former world leaders, toppled Iceland’s prime minister, and recovered more than $1.2 billion, yet the firm’s founders walked free.

• The breach of Mossack Fonseca is thought to have exploited basic flaws such as an outdated WordPress plugin or an SQL injection bug.
• WikiLeaks derided the decision to keep most of the files offline as 1 percent journalism, but the secrecy kept targets from moving money before publication.
• A company linked to billionaire Beny Steinmetz owed more than $700,000 in property taxes to the impoverished city of Koidu in Sierra Leone.
• Iceland’s prime minister, Sigmundur David Gunnlaugsson, secretly co-owned an offshore company holding claims against the failed banks whose creditors he was negotiating with, and he walked out of an interview when confronted.
• In June 2024 a Panamanian judge acquitted the firm’s founders and former employees, ruling that the chain of custody for the leaked digital evidence had been compromised.